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Electrical and Electrochemical Performance Characteristics of Small Commercial Li-Ion Cells

Description: Advanced rechargeable lithium-ion batteries are presently being developed and commercialized worldwide for use in consumer electronics, military and space applications. At Sandia National Laboratories we have used different electrochemical techniques such as impedance and charge/discharge at ambient and subambient temperatures to probe the various electrochemical processes that are occurring in Li-ion cell. The purpose of this study is to identify the component that reduces the cell performance at subambient temperatures. Our impedance data suggest that while the variation in the electrolyte resistance between room temperature and {minus}20 C is negligible the anode electrolyte interfacial resistance increases by an order of magnitude in the same temperature regime. We believe that the solid electrolyte interface (SEI) layer on the carbon anode may be responsible for the increase in cell impedance. We have also evaluated the cells in hybrid mode with capacitors. High-current operation in the hybrid mode allowed fill usage of the Li-ion cell capacity at 25 C and showed a factor of 5 improvement in delivered capacity at {minus}20 C.
Date: December 22, 1998
Creator: Ingersoll, D.; Nagasubramanian, G. & Roth, E.P.
Partner: UNT Libraries Government Documents Department

Energy and power characteristics of Li-ion cells

Description: At Sandia National Laboratories the authors are evaluating the energy and power characteristics of commercially available Li-ion cells. Cells of several different sizes (20 Ah, 1.1 Ah, 0.750 Ah and {approximately}0.5 Ah) and geometries (cylindrical and prismatic) from several manufacturers were studied. The cells were pulsed discharged at increasing currents (50 mA to 1,000 mA) over a range of temperatures (+35 C to {minus}40 C) and at different states of charge (4.1 V, open circuit voltage (OCV), fully charged, 3.6 V OCV partially discharged and 3.1 V OCV nearly discharged) and the voltage drop was recorded. The voltage drop was small at ambient and near ambient temperatures indicating that the total cell internal impedance was small under these conditions. However, at {minus} 40 C the voltage drop was significant due to an increase in the cell internal impedance. At a given temperature, the voltage drop increases with decreasing state-of-charge (SOC) or OCV. The cell impedance and other electrochemical properties as a function of temperature and SOC were also measured. The Ragone data indicate that the specific power and specific energy of Li-ion cells of different sizes are comparable and therefore scaling up to {approximately}20 Ah does not affect either the energy or the power.
Date: June 8, 1998
Creator: Nagasubramanian, G.; Jungst, R.G.; Ingersoll, D.; Doughty, D.H.; Radzykewycz, D. & Hill, C.
Partner: UNT Libraries Government Documents Department

Spinel electrodes for rechargeable lithium batteries.

Description: This paper gives a historical account of the development of spinel electrodes for rechargeable lithium batteries. Research in the late 1970's and early 1980's on high-temperature . Li/Fe{sub 3}O{sub 4} cells led to the evaluation of lithium spinels Li[B{sub 2}]X{sub 4} at room temperature (B = metal cation). This work highlighted the importance of the [B{sub 2}]X{sub 4}spinel framework as a host electrode structure and the ability to tailor the cell voltage by selection of different B cations. Examples of lithium-ion cells that operate with spinel anode/spinel cathode couples are provided. Particular attention is paid to spinels within the solid solution system Li{sub 1+x}Mn{sub 2-x}O{sub 4} (0 {le} x {le} 0.33).
Date: November 10, 1999
Creator: Thackeray, M. M.
Partner: UNT Libraries Government Documents Department

Comparison of the electrochemical properties of several commercial graphites with a templated disordered carbon

Description: A templated carbon was prepared by the pyrolysis of pyrene impregnated into pillared clay (PILC). The electrochemical performance of this was evaluated with the goal of using this material as an anode in Li-ion cells. The reversible capacity was measured as a function of C rate and the cycling characteristics were determined for various intercalation protocols. The performance of this material was compared to that of several commercial graphites tested under the same conditions. The PILC carbon shows great promise as a Li-ion anode if the fade and first-cycle losses can be controlled.
Date: April 11, 2000
Creator: Guidotti, R. A.; Reinhardt, F. W. & Sandi, G.
Partner: UNT Libraries Government Documents Department

The faradaic efficiency of the lithium-thionyl chloride battery

Description: The efficiency of converting chemical energy into electrical energy has been studied for the case of D-size, low and medium rate lithium-thionyl chloride (Li/TC) cells, under DC and various pulsed loads. Microcalorimetric monitoring of the heat output during discharge allowed the direct measurement of the faradaic efficiency, and showed that self-discharge is far more pervasive than previously acknowledged by researchers and battery manufacturers. Evaluations of the cell dynamics prove that current load and temperature fluctuations combine to disrupt the lithium passivation and to greatly enhance self-discharge. Typical faradaic efficiencies for DC range from abut 30% at low current density to 90% at moderate and 75% at high current density. Pulsed current further depresses these efficiency levels, except at very low average current densities. The decreased faradaic efficiency of Li/TC batteries in certain pulse situations needs to be studied further to define the range of applications for which it can be successfully used.
Date: April 1, 1996
Creator: Hoier, S.N. & Eisenmann, E.T.
Partner: UNT Libraries Government Documents Department

Impedance studies on Li-ion cathodes

Description: This paper describes the author's 2- and 3-electrode impedance results of metal oxide cathodes. These results were extracted from impedance data on 18650 Li-ion cells. The impedance results indicate that the ohmic resistance of the cell is very nearly constant with state-of-charge (SOC) and temperature. For example, the ohmic resistance of 18650 Li-ion cells is around 60 m{Omega} for different SOCS (4.1V to 3.0V) and temperatures from 35 C to {minus}20 C. However, the interfacial impedance shows a modest increase with SOC and a huge increase of between 10 and 100 times with decreasing temperature. For example, in the temperature regime (35 C down to {minus}20 C) the overall cell impedance has increased from nearly 200 m{Omega} to 8,000 m{Omega}. Most of the increase in cell impedance comes from the metal oxide cathode/electrolyte interface.
Date: April 17, 2000
Creator: NAGASUBRAMANIAN, GANESAN
Partner: UNT Libraries Government Documents Department

Battery research at Argonne National Laboratory

Description: Argonne National Laboratory (ANL) has, for many years, been engaged in battery-related R and D programs for DOE and the transportation industry. In particular, from 1973 to 1995, ANL played a pioneering role in the technological development of the high-temperature (400 C) lithium-iron disulfide battery. With the emphasis of battery research moving away from high temperature systems toward ambient temperature lithium-based systems for the longer term, ANL has redirected its efforts toward the development of a lithium-polymer battery (60--80 C operation) and room temperature systems based on lithium-ion technologies. ANL`s lithium-polymer battery program is supported by the US Advanced Battery Consortium (USABC), 3M and Hydro-Quebec, and the lithium-ion battery R and D efforts by US industry and by DOE.
Date: October 1, 1997
Creator: Thackeray, M.M.
Partner: UNT Libraries Government Documents Department

Two and Three-Electrode Impedance Studies on 18650 Li-Ion Cells

Description: Two and three electrode impedance measurements were made on 18650 Li-ion cells at different QB temperatures ranging from 35 C to {minus}40 C. The ohmic resistance of the cell is nearly constant the temperature range studied although the total cell impedance increases by an order of magnitude in the same temperature range. In contrast to what is commonly believed, we show from our three-electrode impedance results that, the increase in cell impedance comes mostly from the cathode and not from the anode. Further, the anode and cathode contribute to both the impedance loops (in the NyQuist plot).
Date: August 11, 1999
Creator: Nagasubramanian, Ganesan
Partner: UNT Libraries Government Documents Department

A rapid method for the determination of lithium transference numbers

Description: Lithium ion-conducting polymer electrolytes are of increasing interest for use in lithium-polymer batteries. Lithium transference numbers, the net fraction of current carried by lithium in a cell, are key figures of merit for potential lithium battery electrolytes. The authors describe the Electrophoretic NMR (ENMR) method for the determination of lithium ion transference numbers (T{sub Li}). The work presented is a proof-of-concept of the application of the ENMR method to lithium ion transference measurements for several different lithium salts in gelled electrolytes. The NMR method allows accurate determination of T{sub Li} values, as indicated by the similarity of T{sub Li} in the gelled electrolytes to those in aqueous electrolyte solutions at low salt concentration. Based on calculated tradeoffs of various experimental parameters, they also discuss some conclusions concerning the range of applicability of the method to other electrolytes with lower lithium mobility.
Date: May 1, 1997
Creator: Zawodzinski, T.A. Jr.; Dai, H.; Sanderson, S.; Davey, J. & Uribe, F.
Partner: UNT Libraries Government Documents Department

Novel carbonaceous materials used as anodes in lithium ion cells

Description: The objective of this work is to synthesize disordered carbons used as anodes in lithium ion batteries, where the porosity and surface area are controlled. Both parameters are critical since the irreversible capacity obtained in the first cycle seems to be associated with the surface area (an exfoliation mechanism occurs in which the exposed surface area continues to increase).
Date: September 1, 1997
Creator: Sandi, G.; Winans, R.E. & Carrado, K.A.
Partner: UNT Libraries Government Documents Department

High-temperature sodium nickel chloride battery for electric vehicles

Description: Although the sodium-nickel chloride cell couple has a high voltage (2.59 V) and a high specific energy (790 Wh/kg), the performance of present incarnations of this battery tend to be limited by their power. Because the nickel chloride electrode dominates the resistance and weight of the cell, research on this cell couple at Argonne National Laboratory (ANL) has been primarily directed toward improving both the specific power and energy of the NiCl{sub 2} electrodes. During the course of these investigations a major breakthrough was achieved in lowering the impedance and increasing the usable capacity through the use of chemical additives and a tailored electrode morphology. This improved Ni/NiCl{sub 2} electrode has excellent performance characteristics, wide-temperature operation and fast recharge capability. Modeling studies done on this electrode indicate that a fully developed Na/NiCl{sub 2} battery based on ANL-single tube and bipolar designs would surpass the mid-term and approach the long-term goals of the US Advanced Battery Consortium.
Date: July 1, 1996
Creator: Prakash, J.; Redey, L.; Nelson, P.A. & Vissers, D.R.
Partner: UNT Libraries Government Documents Department

Neutron and X-ray scattering experiments on lithium polymer electrolytes

Description: The authors are carrying out structural, dynamical and transport measurements of lithium polymer electrolytes, in order to provide information needed to improve the performance of secondary lithium battery systems. Microscopically, they behave as liquids under conditions of practical interest. Development of batteries based on these materials has focused on rechargeable systems with intercalation/insertion cathodes and lithium or lithium-containing materials as anodes. The electrolytes are generally composites of a polyethylene oxide (PEO) or another modified polyether and a salt such as LiClO{sub 4}, LiAsF{sub 6} or LiCF{sub 3}SO{sub 3}. Research on electrolyte materials for lithium batteries has focused on synthesis, characterization, and development of practical devices. Some characterization work has been carried out to determine the properties of the ion polymer and ion interactions, principally through spectroscopic, thermodynamic and transport measurements. It is generally believed that ionic conduction is a property of the amorphous phase of these materials. It is also believed that ion association, ion polymer interactions and local relaxations of the polymer strongly influence the ionic mobility. However, much about the nature of the charge carriers, the ion association processes, and the ion polymer interactions and the role that these play in the ionic conductivity of the electrolytes remains unknown. The authors have initiated a combined experimental and theoretical study of the structure and dynamics of lithium polymer electrolytes. They plan to investigate the effects of the polymer host on ion solvation and the attendant effects of ion pairing, which affect the ionic transport in these systems.
Date: September 1, 1997
Creator: Saboungi, M.L. & Price, D.L.
Partner: UNT Libraries Government Documents Department

Thermal characterization of Li-ion cells using calorimetric techniques

Description: The thermal stability of Li-ion cells with intercalating carbon anodes and metal oxide cathodes was measured as a function of state of charge and temperature for two advanced cell chemistries. Cells of the 18650 design with Li{sub x}CoO{sub 2} cathodes (commercial Sony cells) and Li{sub x}Ni{sub 0.8}Co{sub 0.2}O{sub 2} cathodes were measured for thermal reactivity. Accelerating rate calorimetry (ARC) was used to measure cell thermal runaway as a function of state of charge (SOC), microcalorimetry was used to measure the time dependence of thermal output, and differential scanning calorimetry (DSC) was used to study the thermal reactivity of the individual components. Thermal decomposition of the anode solid electrolyte interphase (SEI) layer occurred at low temperatures and contributes to the initiation of thermal runaway. Low temperature reactions from 40 C--70 C were observed during the ARC runs that were SOC dependent. These reactions measured in the microcalorimeter decayed over time with power-law dependence and were highly sensitive to SOC and temperature. ARC runs of aged and cycled cells showed complete absence of these low-temperature reactions but showed abrupt exothermic spikes between 105--135 C. These results suggest that during aging the anode SEI layer is decomposing from a metastable state to a stable composition that is breaking down at elevated temperatures.
Date: May 31, 2000
Creator: ROTH,EMANUEL P.
Partner: UNT Libraries Government Documents Department

Comparison of the electrochemical properties of several commercial graphites with a templated disordered carbon

Description: A templated carbon was prepared by the pyrolysis of pyrene impregnated into pillared clay (PILC). The electrochemical performance of this was evaluated with the goal of using this material as an anode in Li-ion cells. The reversible capacity was measured as a function of C rate and the cycling characteristics were determined for various intercalation protocols. The performance of this material was compared to that of several commercial graphites tested under the same conditions. The PILC carbon shows great promise as a Li-ion anode if the fade and first-cycle losses can be controlled.
Date: March 22, 2000
Creator: GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W. & SANDI,GISELLE
Partner: UNT Libraries Government Documents Department

Instability of Polyvinylidene Fluoride-Based Polymeric Binder in Lithium-Ion Cells: Final Report

Description: Thermal instabilities were identified in SONY-type lithium-ion cells and correlated with interactions of cell constituents and reaction products. Three temperature regions of interaction were identified and associated with the state of charge (degree of Li intercalation) of the cell. Anodes were shown to undergo exothermic reactions as low as 100 degree C involving the solid electrolyte interface (SEI) layer and the LiPF(6) salt in the electrolyte (EC-PC:DEC/IM LiPF(6)). These reactions could account for the thermal runaway observed in these cells beginning at 100 degree C. Exothermic reactions were also observed in the 200 degree C to 300 degree C region between the intercalated lithium anodes, the LiPF(6) salt, and the PVDF. These reactions were followed by a high-temperature reaction region, 300 degree C to 400 degree C, also involving the PVDF binder and the intercalated lithium anodes. The solvent was not directly involved in these reactions but served as a moderator and transport medium. Cathode exothermic reactions with the PVDF binder were observed above 200 degree C and increased with the state of charge (decreasing Li content). The stability of the PVDF binder as a function of electrochemical cycling was studied using FTIR. The infrared spectra from the extracts of both electrodes indicate that PVDF is chemically modified by exposure to the lithium cell electrolyte (as well as electrochemical cycling) in conjunction with NMP extraction. Preconditioning of PVDF to dehydrohalogenation, which may be occurring by reaction with LiPf(6), makes the PVDF susceptible to attack by a range of nucleophiles.
Date: May 1, 1999
Creator: Garcia, M.; Nagasubramanian, G.; Tallant, D.R. & Roth, E.P.
Partner: UNT Libraries Government Documents Department

SYNTHESIS OF A NEW FAMILY OF FLUORINATED BORONATE COMPOUNDS AS ANION RECEPTORS AND STUDIES OF THEIR USE AS ADDITIVES IN LITHIUM BATTERY ELECTROLYTES.

Description: Numerous studies have been done on developing new electrolytes for lithium batteries with high ionic conductivity, and good chemical and electrochemical stability. In addition to the research on new salts and solvents, the use of cation receptors to reduce ion pairing in non-aqueous electrolytes has been considered as an approach to improve the properties of electrolytes. Although both cation and anion receptors enhance the dissociation of ion pairs and increase the conductivity of electrolytes, the use of anion receptors is more attractive for a lithium battery electrolyte because anion receptors increase the lithium transference number in the electrolyte. However, most available neutral anion receptors complex with anions through hydrogen binding and cannot be used in lithium batteries. Recently, we have reported on synthesis of a series of new neutral boron compounds as anion receptors based on the idea that electron-deficient boron would complex the anion of the ion pair. The anion complexation effect of these boron compounds was further enhanced by attaching electron-withdrawing groups. Here we report synthesis of another new family of boronate compounds. The effect of these new compounds on conductivity of lithium salts in non-aqueous solution was studied. The molecular weights of these new boronate compounds are lower than our previously reported boron compounds. Therefore, their effects on conductivity enhancement are superior. They also display high electrochemical stability up to 5 V.
Date: June 8, 2001
Creator: MCBREEN,J.; LEE,H.S. & YANG,X.Q.
Partner: UNT Libraries Government Documents Department

Costs of lithium-ion batteries for vehicles

Description: One of the most promising battery types under development for use in both pure electric and hybrid electric vehicles is the lithium-ion battery. These batteries are well on their way to meeting the challenging technical goals that have been set for vehicle batteries. However, they are still far from achieving the current cost goals. The Center for Transportation Research at Argonne National Laboratory undertook a project for the US Department of Energy to estimate the costs of lithium-ion batteries and to project how these costs might change over time, with the aid of research and development. Cost reductions could be expected as the result of material substitution, economies of scale in production, design improvements, and/or development of new material supplies. The most significant contributions to costs are found to be associated with battery materials. For the pure electric vehicle, the battery cost exceeds the cost goal of the US Advanced Battery Consortium by about $3,500, which is certainly enough to significantly affect the marketability of the vehicle. For the hybrid, however, the total cost of the battery is much smaller, exceeding the cost goal of the Partnership for a New Generation of Vehicles by only about $800, perhaps not enough to deter a potential buyer from purchasing the power-assist hybrid.
Date: August 21, 2000
Creator: Gaines, L. & Cuenca, R.
Partner: UNT Libraries Government Documents Department